Abstract

A method for distortion correction of computer-generated textured images maps vertices and texture coefficients from viewer space to projector space, so that environmental objects are pre-distorted upon the projection raster in order to appear in their proper form and perspective when the raster is projected onto a curved surface in viewer space, and viewed therefrom. Distortion correction is carried out by utilizing a piecewise-linear approximation for smoothly, continuously and closely approximating the required pre-curvature. The viewing space raster is subdivided into a number of triangles, within each of which a linear approximation is applied to the image mapping: the raster faces are first subdivided along the lines of a rectangular grid and the face fragments falling within each rectangle are then subdivided along the grid diagonal. This produces face fragments which are small enough so that a linear approximation provides an accurate transformation of each fragment. Distortion maps, typically computed off-line and stored in a database memory, are utilized to project the edges and texture modulation gradients from view space back into projector space, so that the edges and texture patterns can now be matched at intersections of adjacent triangles, in a manner to be substantially devoid of any abrupt changes, and thus be properly pre-distorted.

Other References

• Patent Abstracts of Japan vol. 16, No. 418, Sep. 2, 1992
• Australian Computer Journal, vol. 19, No. 3, Aug. 1987, pp. 148-15